STRUCTURE OF INSECTS. 295 



The tarsus, or foot (r), is the last division of the 

 limb : it is divided into several joints, which have 

 been supposed to represent those of the toes of 

 quadrupeds. The joints are generally of the hinge 

 kind, but some are met with of a more rounded 

 form, and approaching to that of the ball and 

 socket. The whole structure is most admirably 

 adapted to its exact application over all the ine- 

 qualities of the surfaces on which the insect treads. 

 But as the habits and modes of life of this numerous 

 class are exceedingly diversified, so the form of the 

 feet admits of greater variety than that of any other 

 part of the limb. 



The feet of insects diverge, and spread over a wide 

 surface ; thus extending the base of support so as 

 to ensure the stability of their bodies in the most 

 perfect manner. When the legs are very long, as 

 in the Tipula, the body seems, indeed, more to be 

 suspended than supported by them ; contrary to 

 what obtains in quadrupeds, where the feet are 

 more immediately underneath the points at which 

 they are connected with the trunk. It has been 

 conjectured that the object in furnishing this insect 

 with legs of so great a length is that of enabling it 

 to walk among blades of grass. 



The last joint of the tarsus is generally termi- 

 nated by a double claw, which contributes to fasten 

 the foot, under a variety of circumstances, both of 



side, is placed on the anterior tibia ; the hollow edge corresponding 

 with a similar notch in the first joint of the tarsus ; and through 

 these the insect draws its antennse in order to clean them. In some 

 species of Tenthredo, and some of the Trichloptera, the tarsus is 

 furnished, in the middle of its length, with similar organs. In the 

 Cimbices, the calcaria have a cushion at their apex. 



